The present disclosure generally relates to a Micro Electro Mechanical Systems (MEMS) sensor.
Generally, a MEMS sensor has been variously used in a car, aircraft, mobile communication terminals, toys, and the like and is implemented as 3-axis acceleration and angular velocity sensors which measure X-axis, Y-axis and Z-axis accelerations and angular velocities, a pressure sensor, and the like. The MEMS sensor has been developed to have high performance and be miniaturized to detect fine acceleration.
Among the MEMS sensors, the acceleration sensor may have technical features which convert motions of a mass body and a flexible beam into electrical signals. As a type of the acceleration sensor, there are, for example, a piezoresistive type which detects the motion of the mass body from a change in resistance of a piezoresistance element disposed in the flexible beam, a capacitive type which detects the motion of the mass body from a change in capacitance with a fixed electrode, and the like.
Further, the acceleration sensor in which the mass body is connected to a fixed part through a flexible part may detect a displacement of the mass body or a deformation of the flexible part which occurs by an inertial force applied to the mass body in proportion to the applied acceleration. When acceleration larger than a range of the acceleration to be detected is applied by a mechanical impact such as dropping, an excessive stress is applied to the flexible part, such that the flexible part may be broken. Further, to increase sensitivity, the flexible part may be thinly formed. As a result, the flexible part may be easily damaged.
In the MEMS sensor, the rigidity of the flexible part is reinforced by forming, for instance, a fillet or a chamfer at the end of the flexible part connected to the mass body in a thickness direction, but a fine control is needed to form the fillet or the chamfer and therefore productivity may be reduced.
Further, as another method, there is a method of expanding a width of an end of a flexible part to reduce an impact damage stress. In this case, sensitivity may be decreased and there may be a difficulty in an optimal design and a stress dispersion.